Click here MAX38907/MAX38908 4A, High-Performance LDO … · 2020. 12. 8. · SELC MRG SELA (HIGH)...

General DescriptionThe MAX38907/MAX38908 are fast transient response,high-PSRR nMOS linear regulators that deliver up to 4Aload current.These regulators support a wide input supply range from0.9V up to 5.5V, and BIAS voltage range from 2.7V to 20Vto provide wider supply options in a variety of applications.Output accuracy of ±1% is maintained over line, load, andtemperature variations, requiring only 300mV of input-to-output headroom at full load for a good PSRR. The outputvoltage can be adjusted to a value in the range of 0.6V to5.0V to accommodate customers that desire to specify asingle LDO in the BOM for multiple voltage rails.The MAX38907 is configurable to one of 27 output volt-ages using three digital configuration pins. Additionally,each output voltage selection can be adjusted ±5% formargining. The output voltage on the MAX38908 can beadjusted to a value in the range of 0.6V to 5.0V by usingtwo external feedback resistors. These LDOs are fully pro-tected from damage by internal circuitry that provides pro-grammable inrush current limiting, output overcurrent limit-ing, reverse-current limiting, and thermal overload protec-tion.The MAX38907 is offered in a 20-pin, 5mm x 5mm TQFNpackage, while the MAX38908 is offered in 5 x 3 bump,0.4mm pitch WLP and 14-pin, 3mm x 3mm TDFN pack-ages.

Applications● FPGAs and DSPs● Medical, Audio, and Instrumentation● Server μPs● Portable Cameras● PLCs● Base Stations

Benefits and Features● Delivers Flexible Operating Range

• 0.9V to 5.5V Input Voltage Range• 2.7V to 20V BIAS Voltage Range• 0.6V to 5.0V Programmable Output Voltage• 4A Maximum Output Current• 51mV Dropout at 4A Load Current• 1.6mA Operating BIAS Supply Current

● Reduces Noise and Improves Accuracy• ±1% DC Accuracy over Load, Line, and

Temperature• 28mV, 4A Load-Transient Excursion• 78dB BIAS PSRR at 10kHz• 52dB IN PSRR at 10kHz at 300mV Input-to-Output

Headroom● Enables Ease-of-Use and Robust Protection

• Stable with 10μF (Minimum) Output Capacitance• Programmable Soft-Start Rate• Overcurrent and Overtemperature Protection• Output-to-Input Reverse-Current Protection• Power-OK Status Pin

● Reduces Size, Improves Reliability• 14-Pin (3mm x 3mm) TDFN, 20-Pin (5mm x 5mm)

TQFN, and 5 x 3 Bump, 0.4mm Pitch WLP• -40°C to +125°C Operating Temperature

Ordering Information appears at end of data sheet.

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MAX38907/MAX38908 4A, High-PerformanceLDO Linear Regulators

19-100604; Rev 2; 11/20

https://www.maximintegrated.com/en/storefront/storefront.html

Typical Application CircuitsIN

(1.3V TO 5.5V)

ENABLE

IN

GND

OUT

BYP

POKEN

MAX38908MAX38908

EP FB

OUT(1.0V/UP TO 4A)

R3100kΩ

POK

C322µF

C122µF

R115kΩ

R210kΩ

IN

IN

IN

OUT

OUT

OUT

C247nF

BIASBIAS(2.7V TO 20V)

IN(1.3V TO 5.5V)

ENABLE

IN

GND

OUT

BYP

POK

EN

MAX38907MAX38907

EP

OUTS

OUT(1.0V/UP TO 4A)

R3100kΩ

POK

C322µF

C122µF

IN

IN

IN

OUT

OUT

OUT

C247nF

BIASBIAS(2.7V TO 20V)

SELASELBSELCMRG

SELA (HIGH)SELB (HIGH)

MRG (FLOAT)SELC (FLOAT)

C41µF

C41µF


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TABLE OF CONTENTSGeneral Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

14 TDFN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 620 TQFN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6WLP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Pin Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

20 TQFN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1314 TDFN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14WLP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Functional Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Bypass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Power OK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Undervoltage Lockout (UVLO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Active Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Output Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Select Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Feedback Version . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Input and Output Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Thermal Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25



LIST OF FIGURESFigure 1. Typical POK Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Figure 2. Typical IN UVLO Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Figure 3. Startup into Dropout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21



LIST OF TABLESTable 1. MAX38907 Output Voltage Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Table 2. Recommended Feedback Resistor Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22



Absolute Maximum RatingsIN, FB, OUT, OUTS, BYP, POK, MRG to GND........ -0.3V to +6VBIAS to GND .......................................................... -0.3V to +22VEN, SELA, SELB, SELC to GND................. -0.3V to BIAS + 0.3VOutput Short-Circuit Duration ..................................... ContinuousContinuous Power Dissipation (TA = +70°C) .

TDFN (derate 24.4mW/°C, TA = +70°C).................. 1951.2mWTQFN (derate 33.3mW/°C, TA = +70°C) ................. 2666.7mW

WLP (derate 16.2mW/°C, TA = +70°C) .......................1312mWOperating Temperature Range ...........................-40°C to +125°CMaximum Junction Temperature ......................................+150°CStorage Temperature Range ..............................-65°C to +150°CLead Temperature (Soldering, 10 second) .......................+300°CSoldering Temperature (reflow) ........................................+260°C

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of thedevice at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions forextended periods may affect device reliability.

Package Information

14 TDFNPackage Code T1433+2COutline Number 21-0137Land Pattern Number 90-0063Thermal Resistance, Single-Layer Board:Junction to Ambient (θJA) 54°C/WJunction to Case (θJC) 8°C/WThermal Resistance, Four-Layer Board:Junction to Ambient (θJA) 41°C/WJunction to Case (θJC) 8°C/W

20 TQFNPackage Code T2055+4COutline Number 21-0140Land Pattern Number 90-0009Thermal Resistance, Single-Layer Board:Junction to Ambient (θJA) 48°C/WJunction to Case (θJC) 2°C/WThermal Resistance, Four-Layer Board:Junction to Ambient (θJA) 30°C/WJunction to Case (θJC) 2°C/W

WLPPackage Code N151C2+1Outline Number 21-100372Land Pattern Number Refer to Application Note 1891Thermal Resistance, Four-Layer Board:Junction to Ambient (θJA) 61.65°C/WJunction to Case (θJC) N/A

For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages.



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Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a differentsuffix character, but the drawing pertains to the package regardless of RoHS status.Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using afour-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.

Electrical Characteristics(VIN = 1.5V, VOUT = 1.0V, VBIAS = 10V, TJ = -40°C to +125°C, CIN = 22μF, COUT = 22μF, CBYP = 1nF, unless noted otherwise. (Note1))

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Input Voltage Range VINGuaranteed by Output Accuracy,VOUT < VIN - VDO

0.9 5.5 V

Bias Voltage Range VBIAS 2.7 20 VInput UndervoltageLockout VIN_UVLO VIN rising, 60mV hysteresis 0.35 0.45 0.55 V

Bias UndervoltageLockout VBIAS_UVLO VBIAS rising, 100mV hysteresis 2.45 2.55 2.65 V

Output Voltage Range VOUT Guaranteed by Output Accuracy 0.6 5.0 V

Output Capacitance COUTEffective capacitance required for stabilityand proper operation 10 22 μF

Input Supply Current IQ VEN = 3.6V, VBIAS = 5.0V, IOUT = 0mA 70.5 150 μA

Input Shutdown Current ISD VEN = 0VTJ = +25°C 0.001 1

μATJ = +125°C 1

Bias Supply CurrentIBIAS

VEN = 3.3V, VBIAS = 5.0V, IOUT = 0mA 1.5 4mA

VEN = 3.3V, VBIAS = 5.0V, IOUT = 4A 1.6IBIAS_SD VEN = 0V 0.75 4 μA

Output Accuracy(MAX38907) ACC

IOUT from 10mA to 4A, VIN from VOUT +0.3V to 5.5V, VBIAS > 2.7V, VBIAS fromVOUT + 2V to 20V, VOUT from 0.6V to5.0V

-1 +1 %

Feedback VoltageAccuracy (MAX38908) VFB

IOUT from 10mA to 4A, VIN from VOUT +0.3V to 5.5V, VBIAS > 2.7V, VBIAS fromVOUT + 2V to 20V, VOUT from 0.6V to5.0V

0.594 0.6 0.606 V

Load Regulation IOUT from 0.1mA to 4A, CBYP = 47nF 0.1 %

Load Transient IOUT = 40mA to 4A and 4A to 40mA, di/dt= 1A/μs, COUT = 3 x 10μF, CBYP = 47nF 28 mV

Line Regulation VIN from VOUT + 0.3V to 5.5V, IOUT =1A, CBYP = 47nF 0.04 %/V

Line TransientVIN = 1.0V to 1.2V to 1.0V, 10V/ms VINslew rate, IOUT = 4A, VOUT = 0.8V, CBYP= 47nF

8.2 mV



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Electrical Characteristics (continued)(VIN = 1.5V, VOUT = 1.0V, VBIAS = 10V, TJ = -40°C to +125°C, CIN = 22μF, COUT = 22μF, CBYP = 1nF, unless noted otherwise. (Note1))


Dropout Voltage(MAX38908) (Note 2) VDO

IOUT = 4A,VOUT_NOM = 1.2V

VBIAS = 5.0V,TDFN 79 150

mV

VBIAS = 5.0V, WLP 52VBIAS = 3.3V,TDFN 105 210

VBIAS = 3.3V, WLP 86


VBIAS = 5.0V,TDFN 92 180

VBIAS = 5.0V, WLP 70


VBIAS = 12V,TDFN 79 150

VBIAS = 12V, WLP 51

Current Limit ILIMVOUTS/OUT = 0.9 x VOUT_NOM, VIN -VOUT = 300mV 4.4 5.6 6.8 A

Output NoiseIOUT = 0.5A, 10Hzto 100kHz, VOUT =1.2V

CBYP = 47nF 21.2 μVRMS

IN Power SupplyRejection Ratio PSRR

VIN - VOUT = 0.3V,IOUT = 1A, COUT =4 x 10μF, CBYP =47nF, VBIAS >2.7V, VBIAS =VOUT + 2V, TA =+25°C

f = 1kHz 59

dB

f = 10kHz 52

f = 100kHz 42

BIAS Supply RejectionRatio PSRR

VIN - VOUT = 0.3V,IOUT = 1A, COUT =4 x 10μF, CBYP =47nF, VBIAS =VOUT + 5V, TA =+25°C

f = 1kHz 90

dBf = 10kHz 78

f = 100kHz 69

BYP Capacitor Range CBYPRegulator remains stable; guaranteed bydesign 0.001 0.1 μF

BYP Soft-Start Current IBYP From BYP to GND during startup 50 μA

SELA/B/C InputThreshold (MAX38907)

VIH EN/SEL Rising 1.0 1.6V

VIL EN/SEL Falling 0.4 0.9SELA/B/C InputLeakage Current(MAX38907)

ISEL_LKVEN, VSEL from 0to 20V, VBIAS =20V

TA = +25°C -1 0.001 1μA

TJ = +125°C 0.01

Output Margin AdjustThreshold (MAX38907)

VMRG = 1.8V 4 5 6%

VMRG = 0V -6 -5 -4

MRG Input Threshold(MAX38907)

VIH MRG rising 1.2 1.3 1.4VVIL MRG falling 0.4 0.5 0.6

MRG hysteresis 0.05



Electrical Characteristics (continued)(VIN = 1.5V, VOUT = 1.0V, VBIAS = 10V, TJ = -40°C to +125°C, CIN = 22μF, COUT = 22μF, CBYP = 1nF, unless noted otherwise. (Note1))


MRG Input Current(MAX38907)

VMRG from 0V to5.5V

VMRG = 0V -100 -1μA

VMRG = 5.5V 1 100

EN Input ThresholdVIH EN rising 1.0 1.6

VVIL EN falling 0.4 0.9

EN Input LeakageCurrent IEN_LK

VEN from 0V to5.5V, VBIAS from8V to 20V

TA = +25°C -1 +0.001 +1μA

TJ = +125°C 0.01

POK Threshold VOUT when POKswitches

VOUT rising 88 91 94%

VOUT falling 88POK Voltage, Low VOL IPOK = 1mA 10 100 mV

POK Leakage Current IPOK_LK VPOK = 5.5VTA = +25°C -1 +0.001 +1

μATJ = +125°C 0.01

IN Reverse-CurrentThreshold VOUT = 1.2V, VBIAS = 10V 700 mA

Thermal ShutdownThreshold

TJ when outputturns on/off

TJ rising 165°C

TJ falling 150

Note 1: Limits over the specified operating temperature and supply voltage range are guaranteed by design and characterization, andproduction tested at room temperature only.

Note 2: Dropout voltage is defined as (VIN - VOUT) when VOUT is 95% of its nominal value.



Typical Operating Characteristics(VIN = 1.5V, VBIAS = 10V, VOUT = 1.0V, CIN = 22μF, COUT = 22μF, CBYP = 47nF, CBIAS = 1μF, TA = +25°C, unless otherwise noted.)



Typical Operating Characteristics (continued)(VIN = 1.5V, VBIAS = 10V, VOUT = 1.0V, CIN = 22μF, COUT = 22μF, CBYP = 47nF, CBIAS = 1μF, TA = +25°C, unless otherwise noted.)



Pin Configurations

20 TQFN

5mm x 5mm, 20-LEAD TQFN (MAX38907)TOP VIEW

1

EXPOSED PAD

OUT

181920 1617

876 109

2

3

4

5

15

14

13

12

11

OUT

OUT

OUT

BYP

OUTSPOKMRGENGND

GNDSELCSELBSELANC

IN

IN

IN

IN

BIAS

MAX38907MAX38907



14 TDFN

OUT1

2

3

4

BIAS

IN

GND

EN

EXPOSED PAD

3mm x 3mmTOP VIEW

5

6

7

IN

IN

14

13

12

11

10

9

8

OUT

OUT

BYP

FB

POK

IN OUT

MAX38908MAX38908



WLP

IN

1

A

5 x 3, 0.4mm PITCHTOP VIEW

GND POK

IN BIASIN EN

FB

GND GND GND

OUT OUT OUT BYP

2 3 4 5

B

C

MAX38908MAX38908

Pin DescriptionPIN

NAME FUNCTION20 TQFN 14 TDFN WLP

1, 2, 3, 4 1, 2, 3, 4 A1, A2, A3 IN Regulator Supply Input. Connect to a voltage between 0.9V and5.5V and bypass with a 22μF ceramic capacitor from IN to GND.

5 5 A4 BIASBias Supply Input. Connect to a voltage between 2.7V and 20Vand bypass with a 1μF capacitor from BIAS to GND. BIAS mustbe 2.0V or more above the VOUT target.

6, 16 7 B1, B2, B3,B4 GND Regulator Ground. Bring IN and OUT bypass capacitor GND

connections to this pin for best performance.

7 6 A5 EN

Enable Pin. Connect this pin to a logic signal to enable (VEN high)or disable (VEN low) the regulator output. Connect to BIAS tokeep the output enabled whenever a valid supply voltage ispresent.

8 — — MRG

±5% Output Voltage Margin Adjustment Input. Float for normaloperation. Pull to 0V to cause the output to regulate 5% lower, orpull above 1.4V to cause the output to regulate 5% higher thannominal.

9 8 B5 POKPower-On Reset Output. Connect a pullup resistor from this pin toa supply to create a reset signal that goes high after the regulatoroutput has reached its regulation target voltage.

10 — — OUTS Output Voltage Sense. Connect to OUT where tight voltageregulation is required.

11 10 C4 BYP Bypass Capacitor Input. Connect a 0.001μF to 0.1μF capacitorbetween OUT and BYP to reduce output noise.



Pin Description (continued)PIN

NAME FUNCTION20 TQFN 14 TDFN WLP

12, 13, 14, 15 11, 12, 13, 14 C1, C2, C3 OUTRegulator Output. Sources up to 4A at the output regulationvoltage. Bypass this pin with 22μF ceramic capacitor to GND. It ispulled low with a 70Ω resistance when the regulator is disabled.

17 — — SELC Logic Input 3 Used to Set Output Voltage of the LDO. Connect toGND, BIAS, or float.

18 — — SELB Logic Input 2 Used to Set Output Voltage of the LDO. Connect toGND, BIAS, or float.

19 — — SELA Logic Input 1 Used to Set Output Voltage of the LDO. Connect toGND, BIAS, or float.

20 — — NC No Connect

EP EP — EP Exposed Pad. Connect the exposed pad to a ground plane withlow thermal resistance to ambient to provide best heat sinking.

— 9 C5 FBOutput Voltage Feedback Input. Connect resistor-divider acrossOUT and GND with the center connected to this pin to set anyoutput voltage between 0.6V and 5.0V.



Functional Diagram

VOLTAGESELECT

SELA

SELB

OUTS

EA

BYP

OUT

REF0.6V

BYP

MAX38907 ONLY

FB

CONTROLEN

THERMALPROTECTION

POK

IN

CURRENTLIMIT

REVERSE-CURRENT

PROTECTION

GND

POK THRESHOLD

MAX38908 ONLY

MAX38907 ONLY

MAX38907MAX38907MAX38908MAX38908

SELC

BIAS BIAS

MRGMRG

ACTIVEDISCHARGE

MRG

MRG



Detailed DescriptionThe MAX38907/MAX38908 are fast transient, high-PSRR linear regulators that deliver up to 4A of load current. Theregulators support a wide input supply (0.9V to 5.5V) and BIAS (2.7V to 20V) voltage ranges, making them suitable forvariety of applications. The output voltage regulation accuracy of ±1% is maintained across load, line, and temperaturevariations, requiring only 300mV of input-to-output headroom at full load for good PSRR. The output voltage can beadjusted to a value in the range of 0.6V to 5.0V to accommodate customers that desire to specify a single LDO in theBOM for multiple voltage rails.The MAX38907 is configurable to one of 27 output voltages using three digital configuration pins. In addition, each outputvoltage selection can be adjusted ±5% for margining. The output voltage on the MAX38908 can be adjusted to a valuein the range of 0.6V to 5.0V by using two external feedback resistors. These LDOs are fully protected from damage byinternal circuitry that provides programmable inrush current limiting, output overcurrent limiting, reverse-current limiting,and thermal overload protection.

EnableThe MAX38907/MAX38908 includes an enable pin (EN). The enable signal is an active-high digital signal that enablesthe device when its voltage passes the rising threshold (VEN ≥ VIH (EN)) and disables the device when its voltage isbelow the falling threshold (VEN ≤ VIL (EN)). If a separate shutdown signal is not available, connect EN to BIAS. WhenEN is driven by a host, its bias current will vary with the BIAS supply level. See the Typical Operating Characteristics formore information.

BypassThe capacitor connected from BYP to OUT filters noise at the reference, feedback resistors, and regulator input stage. Itprovides a high-speed feedback path for improved transient response. A 10nF capacitor rolls off noise at around 32Hz.The slew rate of the output voltage during startup is also determined by the BYP capacitor. The MAX38907/MAX38908feature programmable, monotonic, soft-start set by this capacitor. Its use is highly recommended to minimize inrushcurrent into the output capacitor. A 10nF capacitor sets the slew rate to 5V/ms. This startup rate results in a 110mA slewcurrent drawn from the input at startup to charge 22μF output capacitance.The BYP capacitor value can be adjusted from 1nF to 100nF to change the startup slew rate according to the followingformula:Startup Slew Rate = 5V/ms x 10nF/CBYPwhere CBYP is in nF.This slew rate applies until VOUT reaches 75% of the target, after which VOUT slew rate is reduced.Also, note that being a low-frequency filter node, BYP is sensitive to leakage. BYP leakage currents above 10nA causemeasurable inaccuracy at the output and should be avoided.

Power OKThe power-OK (POK) function monitors the voltage at the feedback pin to indicate the output voltage is in regulation. Itsoperation versus the output voltage is shown in Figure 1.The POK pin is open-drain and requires a pullup resistor to an external supply in order to properly report the deviceregulation status to other devices so it can be used for sequencing. Check if the external pullup supply voltage results ina valid logic level for the receiving device or devices.The range of the pullup resistance is between 10kΩ and 100kΩ. Its lower limit comes from the pulldown strength of thePOK transistor, while the higher limit is determined by maximum leakage current at the POK pin.



VOUT

POK RISING THRESHOLD

POK FALLING THRESHOLD

POK

STARTUP A C E SHUTDOWNB D

Figure 1. Typical POK Operation

The POK operation versus the output voltage is shown in Figure 1. Different operating regions are:● A - The device is in regulation.● B - VOUT sags but does not reach the POK falling threshold.● C - The device is in regulation.● D - VOUT sags low enough to cross the POK falling threshold. The POK is driven low until VOUT recovers above the

POK rising threshold.● E - The device is in regulation.

ProtectionThe MAX38907/MAX38908 is fully protected from an output short-circuit by a current-limiting and thermal overloadprotection circuit. If the output is shorted to GND, the output current is limited to 5.6A (typ). Under these conditions, thedevice quickly heats up. When the junction temperature reaches +165°C, a thermal limit circuit shuts the output deviceoff. Once the device cools to +150°C, the output turns back on to reestablish regulation. If the fault persists, the outputcurrent cycles on and off as the junction temperature slews between +150°C and +165°C. Continuously operating in thefault conditions or above +125°C junction temperature is not recommended since long-term reliability may be reduced. Indropout, the current limit will trigger at 7.4A (typ). Once the limit is triggered, the device will limit the current to 5.6A (typ).The thermal protection can also be triggered when the device is exposed to excessive heat in the system causing the dietemperature to reach undesired levels.The MAX38907/MAX38908 provides the reverse-current protection when the output voltage is higher than the input. Ifextra output capacitance is used at the output, a power-down transient at the input would normally cause a large reverse-current through a conventional regulator. The MAX38907/MAX38908 include a reverse-voltage detector that trips whenIN drops 6.5mV below OUT, shutting off the regulator and opening the body diode connection, thus preventing anyreverse current. The reverse current is a current that flows through the body diode of the pass element and is undesireddue to its impact on power dissipation and long-term reliability, especially at higher current levels. The conditions wherethe reverse current can be flowing back to IN are:



• If the device has a large COUT and the input supply collapses quickly; OUT has little or no-load current,• The output is biased when the input supply is not established, or• The output is biased above the input supply.The MAX38907/MAX38908 will block reverse currents that exceed about 0.7A by opening a switch in series with thepass device body diode.

Undervoltage Lockout (UVLO)The MAX38907/MAX38908 undervoltage lockout (UVLO) circuits respond quickly to glitches on IN or BIAS and attemptsto disable the output of the device if either of these rails collapse. The local input capacitance prevents transientbrownouts in most applications.

VIN

UVLO RISING THRESHOLD

UVLO FALLING THRESHOLD

VOUT

STARTUP SHUTDOWNB C IN REGULATIONA

Figure 2. Typical IN UVLO Operation

Figure 2 reflects UVLO operation. The different operation regions are:● STARTUP - The device begins soft-start once the input voltage crosses its UVLO rising threshold, providing the BIAS

voltage is already above its UVLO rising threshold and the device is enabled (VEN > VIH).● A - The device is in regulation.● B - An input supply brownout condition where VIN can sag below the UVLO rising threshold, but not below the falling

threshold. The device is enabled. Note that the output will sag once the device is in dropout.● C - An input supply brownout condition where VIN sags below UVLO falling threshold. The device is disabled when

VIN crosses its UVLO falling threshold. VOUT drops due to load current. The regulator gets enabled again once VINrecovers to the UVLO rising threshold. Note that the output will start to sag once the device is in dropout.

● SHUTDOWN - The output voltage will start to ramp down once the device gets into dropout. It gets disabled when theinput voltage drops below its UVLO falling threshold.

During VIN power-up, the MAX38907/MAX38908 will begin VOUT soft start-after VIN crosses the VIN UVLO risingthreshold. This assures proper VOUT ramp up and transition to regulation. VOUT soft-start rate should be kept at orslower than the VIN slew rate to avoid entering the dropout. In some situations, VIN transients can place the regulator



into dropout. As VIN starts climbing again and the device comes out of the dropout, the output can overshoot, as shownin Figure 3. This condition is avoided by using an enable signal or by increasing the soft-start time with a larger CBYP.

VOUT

VOLT

AGE

VOUT IN REGULATION

VIN

TIME

DROPOUTVOUT = VIN - VDO

VIN = VOUT_NOM + VDO

Figure 3. Startup into Dropout

Active DischargeWhen EN is low or BIAS supply is below its falling UVLO threshold, the MAX38907/MAX38908 connects a 70Ω resistorfrom VOUT to GND in order to discharge the output capacitance.

Output Voltage Selection

Select VersionThe MAX38907 includes configuration pins SELA, SELB, and SELC that are read during power-up to determine theoutput regulation voltage. 27 output voltage settings are available. Table 1 lists the MAX38907 VOUT configurationoptions.In addition, the MAX38907 has an additional pin, MRG, which allows the output voltage to be margined to ±5% withrespect to each selection option. The MRG pin is strapped low or high in the system, or it can be driven dynamically bythe host. Note that the MRG pin cannot be directly strapped to the BIAS supply if the supply is above 5.0V.

Table 1. MAX38907 Output Voltage ConfigurationSELA SELB SELC NOMINAL VOUT (V) VOUT AT MRG LOW (V) VOUT AT MRG HIGH (V)Float Float Float 0.6 0.57 0.63GND Float Float 0.65 0.6175 0.6825BIAS Float Float 0.7 0.665 0.735Float GND Float 0.75 0.7125 0.7875GND GND Float 0.8 0.76 0.84BIAS GND Float 0.85 0.8075 0.8925Float BIAS Float 0.9 0.855 0.945GND BIAS Float 0.95 0.9025 0.9975BIAS BIAS Float 1.0 0.95 1.05



Table 1. MAX38907 Output Voltage Configuration (continued)Float Float GND 1.05 0.9975 1.1025GND Float GND 1.1 1.045 1.155BIAS Float GND 1.15 1.0925 1.2075Float GND GND 1.2 1.14 1.26GND GND GND 1.25 1.1875 1.3125BIAS GND GND 1.3 1.235 1.365Float BIAS GND 1.5 1.425 1.575GND BIAS GND 1.8 1.71 1.89BIAS BIAS GND 2.0 1.9 2.1Float Float BIAS 2.2 2.09 2.31GND Float BIAS 2.5 2.375 2.625BIAS Float BIAS 2.7 2.565 2.835Float GND BIAS 3.0 2.85 3.15GND GND BIAS 3.3 3.135 3.465BIAS GND BIAS 3.6 3.42 3.78Float BIAS BIAS 4.0 3.8 4.2GND BIAS BIAS 4.5 4.275 4.725BIAS BIAS BIAS 5.0 4.75 5.25

Feedback VersionThe MAX38908 uses external feedback resistors to set the output regulation voltage. The output voltage can be set from0.6V to 5.0V. Set the bottom feedback resistor R1 to less than 100kΩ to minimize FB input bias current error. Calculatethe value of the top feedback resistor R2 as follows:R2 = R1 x (VOUT/VFB - 1)where VFB is the feedback regulation voltage of 0.6V.To set the output to 1.0V, for example, R2 should be:R2 = 15kΩ x (1.0V/0.6V - 1) = 10kΩAn R1 of 15kΩ is recommended to optimize noise performance.Values of the resistor-divider and its tolerance will have a direct impact to VOUT accuracy. 1% resistors or better arerecommended. Table 2 shows recommended values for the feedback resistors.

Table 2. Recommended Feedback Resistor ValuesTARGETED OUTPUT

VOLTAGE (V)TOP FEEDBACK RESISTOR

VALUES (kΩ)BOTTOM FEEDBACK RESISTOR

VALUES (kΩ)CALCULATED OUTPUT

VOLTAGE (V)0.8 4.99 15.0 0.7990.9 7.50 15.0 0.9001.0 10.0 15.0 1.01.2 15.0 15.0 1.21.5 22.6 15.0 1.5041.8 30.1 15.0 1.8042.5 47.5 15.0 2.52.7 52.3 15.0 2.692



Table 2. Recommended Feedback Resistor Values (continued)3.0 59.0 14.7 3.0083.3 68.1 15.0 3.3243.6 75.0 15.0 3.64.5 97.6 15.0 4.5045.0 110.0 15.0 5.0



Applications Information

Input and Output CapacitorsThe MAX38907/MAX38908 are designed to have stable operation using low equivalent series resistance (ESR) ceramiccapacitors at the input, output, and bypass pins. Multilayer ceramic capacitors (MLCC) with X7R dialectic are commonlyused for these types of applications and are recommended due to their relatively stable capacitance across temperature.Nevertheless, amount of equivalent capacitance will depend on operating DC voltage, AC voltage ripple, temperature,etc. Therefore, the capacitor data sheet needs to be properly examined.The MAX38907/MAX38908 are designed and characterized for operation with X7R ceramic capacitors of 22µF or greater(10μF or greater of effective capacitance), both at the input and output. These capacitors must be placed as close aspossible to the respective input and output pins to minimize trace parasitics.A combination of multiple output capacitors in parallel will boost the high-frequency PSRR.

Thermal DesignIn order to optimize MAX38907/MAX38908 performance, special consideration is given to the device power dissipationand PCB thermal design. Power dissipation in the regulator depends on the input-to-output voltage difference and loadconditions. It can be calculated by following equation:Loss (W) = (VIN – VOUT) x ILOADOptimal power dissipation can be achieved by carefully choosing input voltage for a given output target rail voltage.The main thermal conduction path for the device is through the exposed pad of the package. As a result, the thermalpad must be soldered to a copper pad area under the device. Thermal-plated vias must be placed inside the thermalPCB pad to transfer heat to different GND layers in the system. The vias should be capped to minimize solder voids. Themaximum power dissipation is determined by using thermal resistance from the device junction to ambient, keeping themaximum junction temperature below +125°C. Thermal properties of the package are given in the Package Informationsection.The first-order power dissipation estimate for a condition of 3.3V IN and 2.5V OUT with a load current of 500mA is:Loss (W) = (VIN – VOUT) x ILOAD = (3.3V – 2.5V) x 0.5A = 0.4WAssuming the MAX38908ATD+, this power dissipation will raise the junction temperature to:TJ = (PD x θJA) + 25°C = (0.4W x 41°C/W) + 25°C = 41.4°C

Ordering InformationPART NUMBER TEMPERATURE

RANGE PIN-PACKAGE FEATURES

MAX38907ATP+ -40°C to +125°C 20-pin, 5mm x 5mmTQFN

4A LDO, enable input, digitally programmable output voltage,adjustable margin, low-noise bypass

MAX38908ATD+ -40°C to +125°C 14-pin, 3mm x 3mmTDFN 4A LDO, enable input, externally adjustable output, low-noise bypass

MAX38908ANL+ -40°C to +125°C 5 x 3 bump, 0.4mmpitch WLP 4A LDO, enable input, externally adjustable output, low-noise bypass

+ Denotes a lead(Pb)-free/RoHS-compliant package.



Revision HistoryREVISIONNUMBER

REVISIONDATE DESCRIPTION PAGES

CHANGED0 7/19 Initial release —

1 2/20 Removed MAX38909 from data sheet, added more Typical OperatingCharacteristics 1–23

2 11/20

Updated General Description, Benefits and Features, Typical Application Circuits,Absolute Maximum Ratings, Electrical Characteristics, Pin Configurations,Functional Diagram, Detailed Description, Applications Information, OrderingInformation

1, 2, 6–9, 13, 17,18, 24

For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.

Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patentlicenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and maxlimits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.


Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2020 Maxim Integrated Products, Inc.

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